EP4247762B1 - Verfahren zur herstellung einer schmelze zur herstellung von künstlichen mineralfasern - Google Patents

Verfahren zur herstellung einer schmelze zur herstellung von künstlichen mineralfasern Download PDF

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EP4247762B1
EP4247762B1 EP21810035.2A EP21810035A EP4247762B1 EP 4247762 B1 EP4247762 B1 EP 4247762B1 EP 21810035 A EP21810035 A EP 21810035A EP 4247762 B1 EP4247762 B1 EP 4247762B1
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Prior art keywords
furnace
gas
ppm
melt
temperature
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English (en)
French (fr)
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EP4247762A1 (de
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Lars Elmekilde Hansen
Haosheng Zhou
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Rockwool AS
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Rockwool AS
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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
    • C03B5/235—Heating the glass
    • C03B5/2353—Heating the glass by combustion with pure oxygen or oxygen-enriched air, e.g. using oxy-fuel burners or oxygen lances
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/12—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture in shaft furnaces
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/04—Manufacture of glass fibres or filaments by using centrifugal force, e.g. spinning through radial orifices; Construction of the spinner cups therefor
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
    • C03B5/235—Heating the glass
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C13/00—Fibre or filament compositions
    • C03C13/06—Mineral fibres, e.g. slag wool, mineral wool, rock wool
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2211/00—Heating processes for glass melting in glass melting furnaces
    • C03B2211/30—Heating processes for glass melting in glass melting furnaces introducing oxygen into the glass melting furnace separately from the fuel

Definitions

  • the invention relates to a method of preparing a mineral melt in a cupola furnace that uses at least one plasma torch to provide heat energy to the furnace.
  • the plasma torch uses nitrogen, carbon monoxide, carbon dioxide, or a mixture thereof as the carrier gas.
  • Methods of preparing a mineral melt for the production of man-made mineral fibres are known to be carried out in shaft furnaces, such as cupola furnaces. They involve heating mineral material in the presence of coke and an oxygen-containing gas to form the mineral melt. It is challenging to produce mineral melts in a process that reduces harmful emissions in the off-gas of a cupola furnace.
  • Cupola furnaces typically comprise a range of temperature zones, including a hot zone, an oxidation zone, a reduction zone, and a preheating zone.
  • the lower portion of the cupola furnace constitutes the hot zone.
  • the hot zone comprises the mineral melt formed in the cupola, which mineral melt is located in the space between the pieces of coke which are resting on the bottom of the cupola and which support the material laying above.
  • the melt temperature in the hot zone is in the range of 1450 °C to 1550 °C, and it takes a relatively long time to change the temperature of a mineral melt at this location. Further, the distance between the top and bottom of the hot zone is relatively large. This is needed to ensure that the correct oxidation zone temperature is maintained in traditional cupola furnaces.
  • the oxidation zone (also known as the combustion zone) is located above the hot zone.
  • the lower portion of the oxidation zone is usually provided with gas inlet nozzles, known as tuyeres, through which preheated air or another oxidation gas is introduced into the furnace.
  • Heating is usually generated by combustion of coke.
  • the combustion of the coke takes place during the movement of the preheated air up through the oxidation zone, and the gas temperature may rise from about 500 °C to about 2,000 °C, thus causing raw material that moves down through the oxidation zone to be heated to its melting point. This melted mineral material flows down into the hot zone at the base of the cupola furnace.
  • the vertical extension of the oxidation zone is determined by the amount of oxygen introduced into the furnace.
  • the reduction zone is above the oxidation zone, and starts at the level where the oxygen introduced through the tuyeres is consumed by combustion of the coke.
  • the temperature is typically between 1,000 °C and 1,500 °C
  • coke reacts with the CO 2 formed in the oxidation zone to form CO in an amount which is double the amount of consumed CO 2 based on volume.
  • the off-gas may be used to heat the raw materials due to be melted in the cupola furnace in the preheating zone.
  • the preheating zone is above the reduction zone.
  • WO 87/06926 relates to a process of producing a mineral melt, in which some of the heating can be provided by use of a plasma torch.
  • CO in the off-gas is reduced. This may be achieved by using coke to provide at least two thirds of the furnace heating energy. The remainder may be provided by a plasma torch amongst other methods.
  • the carrier gases suitable for use with the plasma torch There is no distinction made between the carrier gases suitable for use with the plasma torch.
  • Such advantages may be achieved by providing greater than 50% of the heating energy to the cupola furnace using a plasma torch, wherein the plasma torch uses nitrogen (N 2 ), carbon monoxide (CO), carbon dioxide (CO 2 ), or a mixture thereof as the carrier gas, and water is excluded from any zone of the cupola furnace that is above 750 °C.
  • EP 1431403 describes a direct smelting furnace and process for accommodating a molten metal bath and slag layer when in use.
  • WO 02/070412 describes a waste processing apparatus for processing a column of wate in a processing chamber having one or more gas outlets at an upper part and one or more plasma torches an output end thereof extending into a lower part of the chamber.
  • US 5,046,144 describes a method for the preparation of a melt for the production of mineral wool, where a raw material is introduced at the top of a shaft furnace and heated to melting temperature partly with a hot gas formed by plasma heating and partly with a hot gas formed by combustion of one or more gaseous hydrocarbons, the latter gas stream being introduced at a level at which the temperature does not exceed 1,250 °C and the melt formed is discharged at the bottom of the shaft furnace.
  • US4797142 A teaches a process for preparing a mineral melt in a cupola furnace having a lower hot zone heated exclusively by plasma torches with nitrogen or air carrier gas and an upper zone including lances for oxygen delivery having a temperature below 1400°C.
  • Atmospheric air is mentioned as carrier gas, naturally including water, next to nitrogen implicitly not including water.
  • As the ratio of coke heating and plasma heating a ratio of 2:1 to 5:1 is recommended, corresponding to about 17-33% plasma heating, with 30% being preferred.
  • For the burning of coke air (implicitly including moisture) is used as oxidant, which necessarily leads to water being in the furnace atmosphere.
  • Figure 1 shows a schematic representation of a cupola furnace configuration that may be used to implement the invention.
  • the cupola furnace comprises at least two temperature zones, including a hot zone at the base of the furnace and an oxidation zone above the hot zone,
  • Plasma torches generate thermal plasma using direct current (DC), alternating current (AC), radio-frequency (RF) and other discharges.
  • Thermal plasmas provide heat, which in DC plasma torches is produced by sending an electric arc between two electrodes, through which arc a carrier gas is passed within a constricted opening. This elevates the temperature of the gas to the point that it enters a fourth state of matter, i.e. plasma.
  • Plasma torches may be transferred or non-transferred.
  • the electrodes are inside the housing of the torch. Whereas in a transferred plasma torch one electrode is located outside the housing of the torch, allowing the arc to form outside of the plasma torch and over a greater distance.
  • the plasma torch in the present invention is a non-transferred plasma torch. Most preferably it is a direct current non-transferred plasma torch.
  • Plasma torches may use a variety of carrier gases, such as oxygen, nitrogen, argon, helium, air, hydrogen or mixtures thereof.
  • the carrier gas is selected from the group consisting of nitrogen, carbon monoxide, carbon dioxide, and mixtures thereof.
  • the carrier gas is nitrogen. It has been found that the production of NO x may be significantly reduced when oxygen is excluded from zones of a cupola furnace that comprise nitrogen and are at a temperature of 1,400 °C or above. To help minimise the production of NO x , the carrier gas, at most, should comprise only a trace amount of oxygen.
  • the carrier gas should comprise less than 5 weight% of oxygen, such as less than 2 weight%, preferably less than 0.8 weight%, based upon the total weight of the carrier gas.
  • the carrier gas is devoid of oxygen. This means that there are, at most, only trace amounts of oxygen present.
  • the enthalpy of the carrier gas used in the plasma torch is preferably from 2.0 to 6.0 kWh/Nm 3 , preferable from 3.0 to 5.0 kWh/Nm 3 .
  • the enthalpy is calculated as measured power divided by measured carrier gas flow.
  • the enthalpy is relevant for controlling melt temperature and melt capacity.
  • a cupola furnace useful in the process of the invention may comprise one plasma torch. Alternatively, it may comprise multiple plasma torches, such as two, three, four or more plasma torches.
  • the power of each plasma torch is typically in the region of from 1 to 6 MW.
  • oxygen As used herein, and unless otherwise stated, the terms “oxygen”, “nitrogen”, “carbon monoxide”, “carbon dioxide” and “hydrogen” refer to O 2 , N 2 , CO, CO 2 , and H 2 , respectively.
  • NO x is known in the art, and includes nitrogen oxides, such as nitric oxide (NO) and nitrogen dioxide (NO 2 ).
  • heat energy may also be provided via alternative means.
  • greater than 50% of the furnace heating energy is provided by the plasma torch. It may be preferable for a greater amount of the furnace heating to be provided by the plasma torch, such as greater than 60%, preferably greater than 70%, more preferably greater than 80%, most preferably greater than 90%.
  • the remainder of the heat energy may be provided, for instance, in the traditional way, i.e. by burning fuel, such as natural gas or coke, in air provided by tuyeres.
  • the tuyeres are typically located at the bottom of the oxidation zone.
  • the cupola furnace may comprise one tuyere, or multiple tuyeres, such as two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, or more tuyeres. It is preferable that there are from nine to thirteen tuyeres, most preferably eleven tuyeres. In this case, it is preferable that the tuyeres are equally distributed around the periphery of the furnace, except at the location of the siphon (melt outlet). In any case, it is preferable that no tuyeres are located in the same zone as the plasma torch, i.e. there are no tuyeres in the hot zone. This helps to avoid oxygen being present in a zone of the cupola furnace that is above 1,400°C. It is preferable that heating is provided in the hot zone solely by the plasma torch.
  • the tuyeres may provide air at a rate of 70 to 250 Nm 3 air per ton charge.
  • the aperture of each tuyere through which air flows into the cupola furnace is typically located from 0 up to a maximum of 1 furnace diameter above the plasma torches.
  • the furnace diameter is the internal diameter of the inner chamber of the cupola furnace.
  • the temperature in the oxidation zone of the cupola furnace should be below 1,400 °C.
  • the temperature of the oxidation zone is below 1,300 °C, preferably below 1,200 °C, more preferably below 1,100 °C, even more preferably below a 1,000 °C, especially below 900 °C, particularly below 800 °C.
  • the temperature of the hot zone should be greater than the temperature of the oxidation zone.
  • the temperature in the hot zone may be above 800 °C, preferably above 900 °C, more preferably above 1,000 °C, more preferably above 1,100 °C, more preferably above 1,200 °C, more preferably above 1,300 °C, more preferably above 1,400 °C.
  • the process of the invention may lead to off-gas comprising NO x in an amount of less than 400 ppm, preferably less than 300 ppm, more preferably less than 250 ppm, even more preferably less than 200 ppm, more preferably less than 150 ppm.
  • a further unexpected benefit of heating the hot zone with a plasma torch using carrier gas that is nitrogen, carbon monoxide, carbon dioxide, or a mixture thereof, is that it may significantly reduce the height of the hot zone in comparison to a corresponding cupola furnace that is heated by means other than a plasma torch.
  • the use of a plasma torch has yet an additional advantage in that it significantly reduces the response time needed to change the temperature in certain zones of the cupola furnace, and in particular the temperature of the mineral melt.
  • the mineral melt temperature may be changed within 20 minutes, preferably within 15 minutes, more preferably within 10 minutes when using a plasma torch. This may be a faster temperature change than when other heating means are used.
  • the furnace produces off-gas comprising hydrogen in an amount of less than 20,000 ppm, preferably less than 10,000 ppm, preferably less than 5,000 ppm, preferably less than 2,000 ppm, preferably less than 1,000 ppm, preferably less than 500 ppm, preferably less than 100 ppm, preferably less than 50 ppm. It is most preferable that there is no detectable amount of hydrogen in the off-gas.
  • the amount of coke used in the cupola furnace may be significantly reduced.
  • the amount of coke used may be less than 80% used in an equivalent cupola furnace that does not use a plasma torch.
  • the amount of coke used is less than 70%, such as less than 60%, for instance less than 40%, more preferably less than 20%, most preferably less than 10% of that used in an equivalent cupola furnace that does not use a plasma torch. This has the advantage of reducing emissions in the off-gas, for instance, producing less CO and/or CO 2 in the off-gas
  • the off-gas from cupola furnaces that are heated using plasma torches may comprise N 2 , CO, CO 2 , NO x and H 2 , each of which is a component of the off-gas.
  • the off-gas may comprise additional components, such as water and particles, i.e. solid particles of matter.
  • the off-gas as a whole, or in part may be used in the carrier gas for one or more of the plasma torches.
  • the components of the off-gas may be separated prior to their use as carrier gas.
  • the components of the off-gas may be separated from each other, or the combination of two of more components may be separated from the others components.
  • the carrier gas may comprise at least one component of the off-gas, such as one, two, three, four, five, or more components of the off-gas. It is preferable that the carrier gas comprises the off-gas components N 2 , CO, CO 2 or a combination thereof. Alternatively, the carrier gas may comprise one off-gas component, such as N 2 , CO, or CO 2 .
  • the one or more component of the off-gas may undergo off-gas cleaning prior to its use in the carrier gas. It is preferable that the off-gas cleaning is to remove particles suspended in the off-gas and/or water.
  • the off-gas cleaning may be carried out on the off-gas as a whole, or at least one component thereof once separated from the remainder of the off-gas.
  • the carrier gas may consist of the off-gas, or at least one component of the off-gas. Alternatively, it may comprise the off-gas, or at least one component of the off-gas. In the latter case, additional gas that did not form part of the off-gas may be added to the carrier gas prior to its use. In this case, the carrier gas is "topped up" with additional gas.
  • the mineral melt prepared via the process of the invention may be suitable for the production of man-made vitreous fibres, such as glass fibres or stone fibres. It is preferable that the mineral melt formed is suitable for use to form man-made vitreous fibres (MMVF). Therefore, in the second aspect of the invention there is provided a process for manufacturing MMVF comprising the steps of
  • the fibres may be made from the mineral melt in a conventional manner. Generally, they are made by a centrifugal fibre-forming process. For instance, the fibres may be formed by a spinning cup process in which they are thrown outwardly through perforations in a spinning cup, or mineral melt may be thrown off a rotating disc and fibre formation may be promoted by blasting jets of gas through the mineral melt. Fibre formation may be conducted by pouring the mineral melt onto the first rotor in a cascade spinner.
  • the mineral melt is poured onto the first of a set of two, three or four rotors, each of which rotates about a substantially horizontal axis whereby mineral melt on the first rotor is primarily thrown onto the second (lower) rotor although some may be thrown off the first rotor as fibres, and mineral melt on the second rotor is thrown off as fibres although some may be thrown towards the third (lower) rotor, and so forth.
  • the spinning process uses a cascade spinner.
  • the properties required of a mineral melt to be used in each spinning method are known to those in the art, and the composition of the mineral melt may be tuned to provide those properties. For instance, those skilled in the art are able to select raw materials to be added to the cupola furnace to produce a specific mineral melt composition.
  • the melt is thus formed into a cloud of fibres entrained in air and the fibres are collected as a web on a conveyor and carried away from the fiberizing apparatus.
  • the web of fibres is then consolidated, which can involve cross-lapping and/or longitudinal compression and/or vertical compression and/or winding around a mandrel to produce a cylindrical product for pipe insulation. Other consolidation processes may also be performed.
  • a binder composition is conventionally applied to the fibres, preferably when they are a cloud entrained in air. Alternatively it can be applied after collection on the conveyor but this is less preferred. Conventional types of binder for use with mineral wool fibres may be used.
  • the consolidated web of fibres is passed into a curing device to cure the binder.
  • the curing may be carried out at temperatures from 100 to 300 °C, such as 170 to 270 °C, such as 180 to 250 °C, such as 190 to 230 °C.
  • the curing takes place in a conventional curing oven for mineral wool production wherein hot air is blown through the consolidated web, preferably operating at a temperature of from 150 to 300 °C, such as 170 to 270 °C, such as 180 to 250 °C, such as 190 to 230 °C.
  • the curing may take place for a time of 30 seconds to 20 minutes, such as 1 to 15 minutes, such as 2 to 10 minutes.
  • Typical the curing takes place at a temperature of 150 to 250 °C for a time of 30 seconds to 20 minutes.
  • the curing process may commence immediately after application of the binder to the fibres.
  • the curing is defined as a process whereby the binder composition undergoes a physical and/or chemical reaction which in case of a chemical reaction usually increases the molecular weight of the compounds in the binder composition and thereby increases the viscosity of the binder composition, usually until the binder composition reaches a solid state.
  • the cured binder composition binds the fibres to form a structurally coherent matrix of fibres.
  • the curing of the binder in contact with the mineral fibres may alternatively take place in a heat press.
  • the curing of a binder in contact with the mineral fibres in a heat press has the particular advantage that it enables the production of high-density products.
  • the fibres, and the mineral melt from which they are formed may have an analysis (measured as % by weight of oxides) of elements within the various ranges defined by the following normal and preferred lower and upper limits.
  • the proportion of Fe(2+) in the mineral melt is greater than 80% based on total Fe, preferably at least 90%, more preferably at least 95% and most preferably at least 97% based on total Fe.
  • MMVF is made using a cascade spinner. Further details of these example mineral melts may be found inWO 2012/140173.
  • FeO in a mineral melt or fibre composition refers to the total amount of iron (calculated in terms of FeO) in said melt or composition irrespective of the amount of each oxidation state of the iron present in the composition.
  • the amount of iron in the mineral melt is from 2 to 15 % by weight, preferably 5 to 12% by weight.
  • Cupola furnaces tend to have a reducing atmosphere, which can result in reduction of iron oxides and formation of metallic iron.
  • metallic iron is not incorporated into the mineral melt and fibres and should be removed from the furnace.
  • the conditions in the furnace may be carefully controlled to avoid excess reduction of iron.
  • the process of the invention may be used in the formation of fibres that can be shown to be soluble in physiological saline.
  • Suitable high aluminium, biologically soluble fibres that can advantageously be made using the process of the present invention are described in WO96/14454 and WO96/14274 , and others are described in WO97/29057 , DE-U-2970027 and WO97/30002 .
  • Such fibres preferably have an adequate solubility in lung fluids as shown in vivo tests or in vitro tests, typically conducted in physiological saline buffered to about pH 4.5. Suitable solubilities are described in WO96/14454 . Usually the rate of dissolution is at least 10 or 20 nm per day in that saline.
  • the fibres preferably have sintering temperature above 800 °C, more preferably above 1,000 °C.
  • the melt preferably has a viscosity at fibre forming temperature of 5 to 100 poise, preferably 10 to 70 poise at 1,400°C. Additional embodiments of this example may be found in WO 99/28252 .
  • the mineral melt in this particular example has a viscosity in the range 10 to 30 poises at 1400 °C, more preferably in the range 20 to 25 poises.
  • An advantage of choosing these viscosities is that the resulting MMVF have a smaller diameter than if the viscosity of the melt were higher.
  • the viscosity of the melt may be determined in accordance with ASTM C 965-96.
  • a cupola furnace useful in the process of the invention may comprise the components and zones described above, in addition to the following.
  • the mineral melt forms a pool in the hot zone, from which it is run off via a siphon to a fibre forming process.
  • the mineral melt may be run from the base of the cupola furnace into another chamber where it collects as a pool and from which it is run off to a fibre-forming process.
  • the raw materials may be in the form of briquettes.
  • Briquettes are made in a known manner by moulding a mix of the desired particulate materials and a binder into the desired briquette shape and curing the binder.
  • the binder may be a hydraulic binder, i.e. one that is activated by water, for instance Portland cement.
  • Other hydraulic binders can be used as partial or complete replacement for the cement and examples include lime, blast furnace slag powder, and certain other slags, and even cement kiln dust and ground MMVF shot ( JP-A-51075711 , US 4,662,941 and US 4,724,295 .
  • binders include clay.
  • the briquettes may also be formed with an organic binder such as molasses, for instance as described in WO 95/34514 .
  • Such briquettes may be described as formstones.
  • a cupola furnace for the preparation of a melt according to process of the first aspect of the invention.
  • Such a cupola furnace may comprise the features herein described before.
  • Also described herein is the use of a plasma torch in a cupola furnace to reduce the amount of NO x , CO, CO 2 , and/or hydrogen in the off-gas, in comparison with a corresponding process in which the plasma torch carrier gas is air or oxygen.
  • the use is to reduce the amount of NO x , and/or hydrogen in the off-gas.
  • the MMVF may be formed as a bonded web comprising the MMVF as described above, or MMVF made according to the process described above, or MMVF made using the apparatus described above, and a cured binder composition.
  • the melt formed according to the process of the invention, and man-made fibres (preferably MMVF) made therefore, may be suitable for use in a range of products, such as insulating elements (both thermal and/or acoustic), and fire insulation elements.
  • the drawing in Figure 1 shows a cupola furnace 1 having a feed hopper 2 which communicates with a vessel 3 having a bottom that is constituted by an axially displaceable cone 4. Below the vessel 3 there is a melting chamber which is enclosed by a water-cooled jacket 5.
  • the cupola furnace 1 comprises at its lower end a plane furnace bottom 6 and in a suitable distance above the bottom 6 there is provided a melt outlet 7.
  • a number of plasma torches 8 are built into the furnace wall some distance above the level wherein the melt outlet 7 is placed.
  • an annular air inlet pipe 9 which communicates with a number of tuyeres 10.
  • the cupola furnace 1 has an inner lining at the hot zone, which is made from bricks. The lining covers the furnace bottom 6 and the inner furnace wall to a height at least up to the tuyeres 10.
  • the solid materials i.e. the raw materials, having a composition corresponding to that of the desired melt are fed into the melting chamber through the hopper 2 and the vessel 3, the dosage being effected by suitable adjustment of the cone 4.
  • Carbonaceous material such as coke, may be added with the solid materials, as required.
  • the upper portion of the melting chamber acts as preheating zone as the materials are heated by the ascending smoke gases. From the preheating zone the materials descend down through the oxidation zone of the furnace, the lower limit of which is located at the level wherein air is introduced through the tuyeres 10. Coke is combusted in the oxidation zone so as form CO 2 .
  • the temperature in the oxidation zone is kept at such a level that the temperature of the portion of the preheating zone located immediately above the upper end of the oxidation zone does not exceed 1000°C so as to eliminate or considerably reduce a reaction between the CO 2 formed in the oxidation zone and carbon so as to form CO.
  • the actual melting is effected in the portion of the melting chamber which is located below the oxidation zone and wherein strong heat is introduced by means of the plasma torches 8. The melt formed descends down towards the bottom of the furnace and the melt is discharged through the melt outlet 7.
  • a melt is formed in a plasma fired cupola furnace, in which the plasma torches are provided with either air or N 2 as the carrier gas.
  • the table below shows the cupola conditions for each type of carrier gas, together with the composition of the exhaust gas (in % by volume or ppm).
  • air As carrier gas it is necessary to mitigate NOx formation which is most obviously done by adding liquid propane gas (LPG) through the plasma torch together with the carrier gas. This explains the differences in power and carrier gas flow at the plasma torch. The different amounts of air to the tuyere are caused by these different operating conditions.
  • LPG liquid propane gas
  • the data show that the amount of each component in the off gas listed is significantly reduced when N 2 is used as the carrier gas. In particular, there is a substantial reduction in the amount of NO x and H 2 present in the off-gas. The amount of H 2 produced when N 2 is used as the carrier gas was below the detection limit of the equipment.

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Claims (14)

  1. Verfahren zum Herstellen einer mineralischen Schmelze in einem Kupolofen, wobei
    der Kupolofen wenigstens zwei Temperaturzonen umfasst, die eine heiße Zone am Boden des Ofens und eine Oxidationszone oberhalb der heißen Zone beinhalten,
    (i) der Ofen mit wenigstens einer Winddüse ausgestattet, die eine Sauerstoffquelle in der Oxidationszone bereitstellt;
    (ii) der Ofen wenigstens einen Plasmabrenner umfasst, der als Trägergas Stickstoff, Kohlenmonoxid, Kohlendioxid oder ein Gemisch davon verwendet und eine Plasmaerwärmung in der heißen Zone bereitstellt;
    (iii) mehr als 50 % der Heizenergie des Ofens durch den Plasmabrenner bereitgestellt wird;
    (iv) die Temperatur in der Oxidationszone unter 1400 °C liegt;
    (v) die Temperatur in der heißen Zone höher ist als die Temperatur in der Oxidationszone
    (vi) Wasser im Wesentlichen aus jeder Zone des Ofens ausgeschlossen ist, in der die Temperatur über 750 °C liegt, und
    wobei mineralisches Material dem Ofen zugeführt und geschmolzen wird, um die mineralische Schmelze auszubilden, die sich in dem Boden des Ofens sammelt, und wobei das Verfahren Prozessabgase produziert.
  2. Verfahren nach Anspruch 1, wobei mehr als 60 %, vorzugsweise mehr als 70 %, stärker bevorzugt mehr als 80 %, am stärksten bevorzugt mehr als 90 % der Heizenergie des Kupolofens durch den Plasmabrenner bereitgestellt wird.
  3. Verfahren nach Anspruch 1 oder 2, wobei die Temperatur in der Oxidationszone unter 1.300 °C, vorzugsweise unter 1.200 °C, stärker bevorzugt unter 1.100 °C, noch stärker bevorzugt unter 1.000 °C, insbesondere unter 900 °C, insbesondere unter 800 °C liegt.
  4. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Heizen in der heißen Zone ausschließlich durch den Plasmabrenner bereitgestellt wird.
  5. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Temperatur in der heißen Zone über 800 °C, vorzugsweise über 900 °C, stärker bevorzugt über 1.000 °C, stärker bevorzugt über 1.100 °C, stärker bevorzugt über 1.200 °C, stärker bevorzugt über 1.300 °C, stärker bevorzugt über 1.400 °C liegt.
  6. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Trägergas-Enthalpie 2,0 bis 6,0 kWh/Nm3, vorzugsweise 3,0 bis 5,0 kWh/Nm3 beträgt.
  7. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Schmelze die folgende Zusammensetzung, ausgedrückt als Oxide, in Gew.-% aufweist: SiO2 35-50, vorzugsweise 38-48, stärker bevorzugt 33-44 Al2O3 12-30, vorzugsweise 15-28, stärker bevorzugt 16-24 TiO2 bis zu 2 Fe2O3 2-12 CaO 5-30, vorzugsweise 5-18 MgO 0-15, vorzugsweise 1-8 Na2O 0-15 K2O 0-15 P2O5 0-3 MnO 0-3 B2O3 0-3,
    wobei der Anteil an Fe(2+) in der Schmelze vorzugsweise größer als 80 % auf Grundlage des gesamten Fe ist, vorzugsweise wenigstens 90 %, stärker bevorzugt wenigstens 95 % und am stärksten bevorzugt wenigstens 97 % auf Grundlage des gesamten Fe.
  8. Verfahren nach einem der vorhergehenden Ansprüche, wobei Sauerstoff aus Zonen eines Kupolofens ausgeschlossen wird, die Stickstoff umfassen und sich auf einer Temperatur von 1.400 °C oder darüber befinden, sodass der Ofen Prozessabgase produziert, die NOx in einer Menge von weniger als 400 ppm, vorzugsweise weniger als 300 ppm, stärker bevorzugt weniger als 250 ppm, noch stärker bevorzugt weniger als 200 ppm, noch stärker bevorzugt weniger als 150 ppm umfassen.
  9. Verfahren nach einem der vorhergehenden Ansprüche, wobei Wasser aus jeder Zone in dem Ofen, die eine Temperatur von über 750 °C aufweist, ausgeschlossen wird, sodass der Ofen Prozessabgase produziert, das Wasserstoff in einer Menge von weniger als 20.000 ppm, vorzugsweise weniger als 10.000 ppm, vorzugsweise weniger als 5.000 ppm, vorzugsweise weniger als 2.000 ppm, vorzugsweise weniger als 1.000 ppm, vorzugsweise weniger als 500 ppm, vorzugsweise weniger als 100 ppm, weniger als 50 ppm umfasst, wobei am stärksten bevorzugt keine nachweisbare Menge an Wasserstoff in dem Prozessabgas vorhanden ist.
  10. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Trägergas Stickstoff ist.
  11. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Trägergas wenigstens eine Komponente der Prozessabgase umfasst.
  12. Verfahren nach Anspruch 11, wobei die wenigstens eine Komponente der Prozessabgase vor ihrer Verwendung als Trägergas einer Prozessabgasreinigung unterzogen wird, wobei die Prozessabgasreinigung vorzugsweise der Entfernung von Partikeln und/oder Wasser dient.
  13. Verfahren nach Anspruch 11 oder 12, wobei das Trägergas aus der wenigstens einen Komponente der Prozessabgase besteht.
  14. Verfahren zum Herstellen von künstlichen glasartigen Fasern (MMVF), umfassen die Schritte von:
    (i) Ausbilden einer Schmelze unter Verwendung eines Verfahrens nach einem der Ansprüche 1 bis 13;
    (ii) Zerfasern der Schmelze mittels eines internen oder externen Spinnverfahrens; vorzugsweise unter Verwendung einer Kaskadenspinnmaschine; und
    (iii) Sammeln der ausgebildeten Fasern.
EP21810035.2A 2020-11-19 2021-11-19 Verfahren zur herstellung einer schmelze zur herstellung von künstlichen mineralfasern Active EP4247762B1 (de)

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JPS5175711A (ja) 1974-12-27 1976-06-30 Nippon Steel Chemical Co Garasugenryozoryuho
US4662941A (en) 1985-10-21 1987-05-05 Sheridan Corporation Mineral wool waste cement
DE3604782A1 (de) 1986-02-13 1987-08-20 Siemens Ag Vorrichtung zum pressschweissen paketierter metallfolien
DK222686D0 (da) 1986-05-14 1986-05-14 Rockwool Int Mineraluldsfremstilling
DK158382C (da) * 1987-10-15 1990-10-22 Rockwool Int Fremgangsmaade ved fremstilling af en smelte til dannelse af mineraluld samt apparat til udoevelse af fremgangsmaaden
GB9412007D0 (en) 1994-06-15 1994-08-03 Rockwell International A S Production of mineral fibres
DE69506277T2 (de) 1994-11-08 1999-04-22 Rockwool Int Synthetische glasfasern
DE19604238A1 (de) 1996-02-06 1997-08-07 Gruenzweig & Hartmann Mineralfaserzusammensetzung
FI960705A (fi) 1996-02-16 1997-08-17 Paroc Oy Ab Mineraalikuitu
JP2001524447A (ja) 1997-12-02 2001-12-04 ロックウール インターナショナル アー／エス 鉱物繊維製造用ブリケット及びそれらの使用
IL141814A (en) * 2001-03-05 2006-08-20 David Pegaz Facility for waste treatment with cell for oxygen mixing
EP1431403A1 (de) * 2002-07-10 2004-06-23 Corus Technology BV Direktschmelzanlage sowie Verfahren
SI2697178T1 (sl) 2011-04-13 2020-02-28 Rockwool International A/S Procesi za oblikovanje ročno izdelanih steklenih vlaken
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